Petroleum Reservoir Evaluation and Development >
2023 , Vol. 13 >Issue 4: 424 - 432
DOI: https://doi.org/10.13809/j.cnki.cn32-1825/te.2023.04.003
Numerical simulation study on the influence of coal rock fracture morphology on seepage capacity
Received date: 2023-03-31
Online published: 2023-09-01
The fracture network developed in coal rock serves as the primary channel for gas migration, significantly influencing the seepage capacity of coal reservoir. The geometric characteristics of fracture plays a crucial role on determining the flow characteristics of coal-bed methane. To study this, a two-dimensional fracture network model of coal rock was established using COMSOL Multiphysics simulation software, focusing on the coal samples of Baode block as the research subject. The effects of fracture length, density, opening degree and angle on production were investigated, providing valuable theoretical guidance for enhancing coal-bed methane production. The results indicate that fracture length, density, and opening degree have a positive correlation with the seepage capacity of coal rock, while the angle with the flow direction negatively impacts it. However, with the increase of length, density and opening degree, the improvement in flow rate slows down, and the effect of increasing single factor to improve coal-bed methane mining can be neglected, making it difficult to control the cost-benefit ratio. Among the factors influencing outlet, angle and density exert a more significant effect than length and opening degree. Considering the surface directional well plus the high pressure hydraulic cutting method, we can enhance the efficiency of coalbed methane development. This approach connects the natural fracture system using directional borehole and hydraulic slot, fully utilizing the permeability advantage of parallel surface cutting direction. The high-pressure hydraulic cutting process induces cracks in the coal seam, increasing the number and connectivity of diversion channels, thereby bolstering the production of coal-bed methane.
Leiting SHI , Qiming ZHAO , Zhenyu REN , Shijie ZHU , Shanshan ZHU . Numerical simulation study on the influence of coal rock fracture morphology on seepage capacity[J]. Petroleum Reservoir Evaluation and Development, 2023 , 13(4) : 424 -432 . DOI: 10.13809/j.cnki.cn32-1825/te.2023.04.003
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